Iago López Galeiras 2e13ba54a2 fs, proc: introduce CONFIG_PROC_CHILDREN ... Commit 818411616b ("fs, proc: introduce /proc/<pid>/task/<tid>/children entry") introduced the children entry for checkpoint restore and the file is only available on kernels configured with CONFIG_EXPERT and CONFIG_CHECKPOINT_RESTORE. This is available in most distributions (Fedora, Debian, Ubuntu, CoreOS) because they usually enable CONFIG_EXPERT and CONFIG_CHECKPOINT_RESTORE. But Arch does not enable CONFIG_EXPERT or CONFIG_CHECKPOINT_RESTORE. However, the children proc file is useful outside of checkpoint restore. I would like to use it in rkt. The rkt process exec() another program it does not control, and that other program will fork()+exec() a child process. I would like to find the pid of the child process from an external tool without iterating in /proc over all processes to find which one has a parent pid equal to rkt. This commit introduces CONFIG_PROC_CHILDREN and makes CONFIG_CHECKPOINT_RESTORE select it. This allows enabling /proc/<pid>/task/<tid>/children without needing to enable CONFIG_CHECKPOINT_RESTORE and CONFIG_EXPERT. Alban tested that /proc/<pid>/task/<tid>/children is present when the kernel is configured with CONFIG_PROC_CHILDREN=y but without CONFIG_CHECKPOINT_RESTORE Signed-off-by: Iago López Galeiras <iago@endocode.com> Tested-by: Alban Crequy <alban@endocode.com> Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kees Cook <keescook@chromium.org> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Serge Hallyn <serge.hallyn@canonical.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Djalal Harouni <djalal@endocode.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2015-06-25 17:00:37 -07:00
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calibrate.c	kernel: add calibration_delay_done()	2014-06-16 12:47:39 -06:00
do_mounts_initrd.c	usermodehelper: split remaining calls to call_usermodehelper_fns()	2013-04-30 17:04:06 -07:00
do_mounts_md.c	init: disable sparse checking of the mount.o source files	2012-05-31 17:49:27 -07:00
do_mounts_rd.c	initramfs: support initramfs that is bigger than 2GiB	2014-08-08 15:57:26 -07:00
do_mounts.c	init: fix regression by supporting devices with major:minor:offset format	2015-05-05 12:31:37 -04:00
do_mounts.h
init_task.c	sched/rt: Move rt specific bits into new header file	2013-02-07 20:51:08 +01:00
initramfs.c	init/initramfs.c: resolve shadow warnings	2014-10-14 02:18:22 +02:00
Kconfig	fs, proc: introduce CONFIG_PROC_CHILDREN	2015-06-25 17:00:37 -07:00
main.c	ACPI / init: Switch over platform to the ACPI mode later	2015-06-10 23:51:27 +02:00
Makefile	init_task: Replace CONFIG_HAVE_GENERIC_INIT_TASK	2012-05-05 13:00:46 +02:00
noinitramfs.c	init: mark __user address space on string literals	2010-10-26 16:52:15 -07:00
version.c	copy address of proc_ns_ops into ns_common	2014-12-04 14:34:47 -05:00